The man accused of firing the shot that killed a 12-year-old Hempstead girl pleaded not guilty today as investigators announced that they believe a gang-related dispute prompted the shooting.

Jakwan Keller, 20, is charged with second-degree murder, criminal weapon possession and criminal use of a firearm in the October slaying. He was ordered held without bail today at an emotional arraignment hearing that was attended by his family and the victim's.

As News 12 has reported, 12-year-old Dejah Joyner died after she was struck in the head by a stray bullet that came through a window of her Dartmouth Street home. She was eating dinner when she was hit.

Keller was taken into custody Sunday morning after a three-month investigation. Investigators said at Monday's press conference that Keller is a member of the Parkside Bloods gang, and that the intended target of the shooting was a member of the rival Highpoint Bloods gang.

Police say the rival member had stolen a hoverboard that belonged to Keller's brother a few days earlier. That rival was in the vicinity of Joyner's home when the shot was fired, police say.

"This should be a message to the members of the gangs in this county: these violent, heinous acts will not be tolerated," Nassau Police Commissioner Thomas Krumpter said of Keller's arrest.

Police say they received more than 43 calls about the case to the Crime Stoppers tip line, and 22 had value that helped lead to Keller's arrest. Video from the area around the time of the shooting was also given to police by residents, which also helped crack the case.

As News 12 has reported, Hempstead Village and Nassau County Crime Stoppers had offered a $75,000 reward for information. Joyner's death sparked outrage and anti-violence rallies in the community.

Dartmouth Street was renamed Dejah Joyner Street to honor the girl. At the time, Mayor Wayne Hall said he hoped the sign would continuously remind people to speak up with any information that could help police catch her killer.

Authorities say Keller was arrested back in 2013 for evading police in a stolen vehicle, crashing into a cop car and then allegedly trying to run down an officer. That officer opened fire at the car before jumping out of the way, according to police. A police press release from the time said that Keller also resisted arrest as he was apprehended.

Records indicate that Keller filed a civil rights suit in 2014 against Nassau County, Nassau police, the Village of Hempstead and Hempstead police. His lawsuit stemmed from his 2013 arrest, and it claimed that police shot at him and then beat him as they took him into custody, leaving his face "completely unrecognizable." The lawsuit claimed excessive force was used, and it sought unspecified damages.

Keller will remain behind bars in the Joyner case until his next court appearance on Wednesday.